Scientists believe that at one time humans grew tails. Now, the majority of humans have evolved to no longer grow tails except in rare instances.
It is still possible for humans to grow tails. A human embryo may grow a tail called a prenatal tail but this usually disappears during the course of embryo development. The embryonic tail will grow into the tail bone or coccyx which is located at the end of the spine.
In very rare cases, the embryonic tail may not disappear and a baby may be born with an actual tail. This is a true human tail.
A true human tail contains tissues, muscles, blood vessels, nerves and is covered by skin. It does not contain any bone or cartilage and it is not a part of the spinal cord. The tail can also move and contract and can grow as long as 5.2 inches.
The occurrence of a true human tail is supposed to be a rare event with only about 40 or so cases reported in the literature.
In one reported case in the literature, a baby girl was born with a human tail. The tail was 3 inches when the baby was born and then rapidly grew to more than 4 inches long.
There was no specific reason that could have resulted in the growth of the tail. The pregnancy was normal with no history of illness, exposure to radiation, or drug intake. The child was also clinically. normal except for the growth of the tail.
As a solution, the baby's tail was excised with surgery and the baby recovered normally. Surgery seems to be the best solution for the removal of the tail.